Plain English Meaning

The horizontal tail is one solid piece that tilts up and down as a unit to make the airplane's nose pitch up or down. There is no separate small flap on the back of it -- the whole thing moves.

Full Definition

A horizontal tail surface built as a single, continuous moving panel that pivots as a whole to provide pitch control, rather than being split into a fixed stabilizer with a separate hinged elevator attached to its trailing edge. On airplanes equipped this way, the entire surface rotates about a lateral pivot point in response to control wheel or stick inputs. This configuration is the defining feature of a stabilator.